1. Field of the Invention
This invention relates to a switch device for a transmission, and a transmission using the switch device.
2. Description of the Related Art
To ensure the safety of vehicular travel, a signal system of a transmission has so far used a transmission abnormality detecting device which detects the abnormality of the signal system based on whether the same signal is sent by two detecting means of an electric system and a mechanical system. Various switches such as a mechanical hydraulic switch and an electrical inhibitor switch are used as the detecting means of the abnormality detecting device.
As the abnormality detecting device provided with such two switches, namely, a so-called dual-system switch device, the following device, for example, is known: This is a failure detecting device for an automatic transmission which switches shift by engaging and releasing a plurality of friction elements. The failure detecting device is equipped with a selector detecting means (inhibitor switch) for detecting a driving range selected by a driver's operation of a shift selector; and a hydraulic pressure detecting means (hydraulic switch) for detecting a hydraulic pressure exerted on the friction element and sending a hydraulic pressure detection signal. Configured in this manner, this failure detecting device detects a range detection failure based on inconsistency between the driving range indicated by a selector detection signal and the driving range indicated by the hydraulic pressure detection signal upon detection of the hydraulic pressure exerted on the friction element (for example, Patent Document 1).    Patent Document 1: JP-A-2005-344805 (see claim 1)